#!/usr/bin/lua

local function read_scan()
    local h = io.popen("ubus call iwinfo scan '{\"device\":\"radio0\"}' 2>/dev/null")
    local raw = h:read("*a")
    h:close()
    return raw
end

local function jsondec(s)
    local json = require("luci.jsonc")
    return json.parse(s)
end

local function jsonenc(t)
    local json = require("luci.jsonc")
    return json.stringify(t)
end

io.write("Content-Type: application/json\r\n\r\n")

local raw = read_scan()
local data = raw and jsondec(raw)

if not data or not data.results then
    io.write(jsonenc({ ok = false, error = "scan failed or no results" }))
    os.exit(0)
end

local best = {}
for _, n in ipairs(data.results) do
    local ssid = n.ssid
    if ssid and ssid ~= "" then
        local prev = best[ssid]
        if not prev or (n.signal or -999) > prev.signal then
            best[ssid] = {
                ssid = ssid,
                signal = n.signal or -999,
                quality = n.quality or 0,
                quality_max = n.quality_max or 70,
                band = n.band,
                channel = n.channel,
                secured = n.encryption and n.encryption.enabled or false,
            }
        end
    end
end

local list = {}
for _, v in pairs(best) do list[#list+1] = v end
table.sort(list, function(a, b) return a.signal > b.signal end)

io.write(jsonenc({ ok = true, networks = list }))